This
is a widely diverse genus of trees with
compound, opposite leaves. Traditionally, may of
the common species made nice landscape trees
especially for wet areas.

However, in 2002, an
insect called the
Emerald Ash
Borer (EAB) was discovered in Michigan. The
larvae of this pest which is thought to have
come from
China, burrows through the cambium
layer of ash trees and, eventually, kills the
tree.

As of 2010, over 20 million ash trees have
been killed and, despite government efforts, it
is spreading throughout the Midwest. As a
result, ash trees are no longer recommended for
use in the landscape and several states have
banned their sales.